Track lights are long strips of “U” shaped aluminum lengths, which contains grooves on the inside.
These grooves are designed in a way that fits two runs of non-conductive material, either plastic or rubberized insulators, that run inside all the way through the track.
In turn, these lengths of rubber, protect and hold tight, strips of copper, that bring power from and to an electrical circuit.
The whole system works together, allowing the entire track to be a surface in which you can plug a track light and get power to it in a safe manner.
The electrical leads never stay exposed, and you can plug in as many light fixtures as the system allows by manufacturer instructions.